Inducing acute lung injury by deposition of IgG immune complexes, we will evaluate four aspects of the lung inflammatory response: role of previously unstudied adhesion molecules; role of CC chemokines; signal transduction events involving NFkappaB (and IkappaBalpha) in lung and effects of regulatory cytokines on this signal transduction process; and, protective roles of macrophage up-regulation of mRNA and protein for CD11c and alphad (CD11d), the extent to which blocking of engagement of these adhesion molecules by antibodies affects the inflammatory response, and mechanisms by which engagement of these adhesion molecules lead to lung injury. Endpoints for all studies will be albumin leak into lung, neutrophil accumulation, and TNFalpha levels in bronchoalveolar (BAL) fluids. Regarding chemokines, we will clone and then evaluate the roles of rat CC chemokines (MIP-1beta, MCP-1 and RANTES) in lung injury by assessing changes in mRNA and protein levels in lung and effects of antibody-induced blockade of these chemokines. Mechanisms by which these chemokines bring about their effects will be evaluated. Signal transduction events in the lung inflammatory model will focus on NFkappaB activation and the dependency of NFkappaB activation on TNFalpha, neutrophils and oxidants. Related studies will determine the extent to which regulatory cytokines (IL-6, IL-10, IL-13) inhibit lung inflammatory reactions by blocking NFkappaB activation (translocation) in vivo. We will assess if the effects of these regulatory cytokines are related to preservation of IkappaBalpha levels within lung. We will also determine if in vitro inhibitors of NFkappaB activation inhibit in vivo lung injury. Finally, we will clone and express rat tissue inhibitor of metalloprotease-2 (TIMP-2) and secreted leukocyte protease inhibitor (SLPI) amd develop blocking antibodies to these proteins. We will then measure up-regulation of TIMP-2 and SLPI and protein in the course of the lung inflammatory response and determine the effects of in vivo blocking of these anti-proteases. If, as expected, blockade of TIMP-2 or SLPI intensified lung injury, the mechanism(s) by which this occurs will be evaluated. This study should define the role of endogenous protease inhibitors in lung inflammatory reactions. Collectively, this information should significantly extend our understanding of the lung inflammatory response and how it is triggered and regulated.